The 2000 MY is Bose (for the car in question) but this doesn't really matter. The head unit is the same. The head unit is the same from 2000-2005 with the following notes:
Depending on vintage there is an AM/FM/Cassette, AM/FM/CD and AM/FM/CD/Cassette.
In 2003 there is a change from the "AM/FM" button to "BAND" for support of XM radio.
In 2004 there was the introduction of black versus gray buttons.
2000-2001 Have a Bose amp in the SSEi, no external amp in the SE or SLE.
2002-2003 Have a Monsoon amp in the SSEi, no external amp in the SE or SLE.
2004-2005 Have a Monsoon amp in the GXP, no external amp in the SE or SLE.
And then of course there'* one GXP out there with the Bose Luxury amp and Touch Screen navigation radio
Grand Prix radios will not mount or work correctly in the 2K+ Bonneville, nor will pre-2K Bonneville radios.